Hair growth problems are wide-spread. In addition to pattern baldness, which may occur in both males and females, hair loss can be induced by drugs, such as chemotherapy drugs, or by chemical or physical damage, such as by certain hair products or styling techniques. Hair loss may also be triggered by systemic diseases, autoimmune conditions, nutritional deficiencies and physical stress, such as during pregnancy, due to surgery, or due to weight loss. It may also be induced by psychological stress.
Available treatments to promote hair growth are limited. For example, minoxidil, while relatively safe, is only moderately effective. The 5-alpha reductase inhibitor finasteride is not indicated for women or children and has negative side effects. The use of certain polypeptides to promote hair growth has been suggested. (See e.g., U.S. Pat. No. 7,335,641, U.S. Pat. No. 7,524,505, U.S. Pat. No. 7,485,618, and U.S. Patent Application No. 2008/0139469, now U.S. Pat. No. 7,589,060.) To date, the only permanent solution to hair loss is hair transplant surgery, which is both expensive and invasive. Thus, there remains a need in the art for additional agents for promoting hair growth. The present invention relates to a method of promoting hair growth comprising administering a fibroblast growth factor receptor 4 (FGFR4) extracellular domain (ECD) to a subject in an amount sufficient to promote hair growth.
Fibroblast growth factors (FGFs) and their receptors (FGFRs) are a highly conserved group of proteins with diverse functions. The FGFR family comprises four major types of receptors, FGFR1, FGFR2, FGFR3, and FGFR4. To date, there are 22 known FGFs, each with the capacity to bind one or more FGFRs. See, e.g., Zhang et al., J. Biol. Chem. 281:15, 694-15,700 (2006). Each FGFR binds to several FGFs, and the different FGFRs may differ from each other both in the selection of FGFs to which they bind as well as in the affinity of those interactions.
The FGFRs are transmembrane proteins having an extracellular domain (ECD), a transmembrane domain, and an intracytoplasmic tyrosine kinase domain. Each of the ECDs contains either two or three immunoglobulin (Ig) domains. When there are three Ig domains, they are referred to as D1, D2, and D3 domains. Receptors having two Ig domains typically lack D1. Extracellular FGFR activation by FGF ligand binding to an FGFR initiates a cascade of signaling events inside the cell, beginning with oligomerization of the receptor and activation of receptor tyrosine kinase activity. Structural studies of FGFR-FGF complexes have shown that FGF ligands interact extensively with the D2 domain, the D3 domain, and the linker region connecting the D2 and D3 domains of an FGFR ECD.
In experiments to determine whether an FGFR4 ECD fusion molecule exhibited antitumor activity in a cancer xenograft model, the inventors discovered that an FGFR4 ECD fusion molecule promoted hair growth at the shaved site where the tumor cells were injected. See Example 9 and FIG. 3. In subsequent experiments, both a native FGFR4 ECD fragment fusion molecule (“R4Mut4”) and an FGFR4 ECD variant fusion molecule (“ABMut1”) that retained FGFR4 ECD ligand binding activity promoted hair growth when administered systemically in mice. See Examples 7, 8, 10, and 11, Tables 2 and 3, and FIG. 4. Experiments in which ABMut1 or agarose beads bound to ABMut1 were subcutaneously injected into the flank of shaved mice showed that local delivery of ABMut1 also promoted hair growth. Further experiments demonstrated that systemic delivery of ABMut1 could also induce anagen in hair follicles, specifically elongation of the dermal papilla into the fatty layer of the dermis. See Example 12 and FIG. 5. Furthermore, hair growth in a shaved mouse model increased with dose of ABMut1. See Example 15 and FIG. 7. In contrast, FGFR1 ECD and FGFR2 ECD fusion molecules did not promote visible hair growth in a shaved mouse model. See Examples 13 and 14 and FIG. 6.
In certain embodiments, a method of promoting hair growth comprising administering an FGFR4 ECD to a subject in an amount sufficient to promote hair growth is provided. In certain embodiments, the FGFR4 ECD is a native FGFR4 ECD. In certain embodiments, the FGFR4 ECD is an FGFR4 ECD variant. In certain embodiments, the FGFR4 ECD is an FGFR4 ECD fragment. In certain embodiments, the FGFR4 ECD is a native FGFR4 ECD fragment. In certain embodiments, the FGFR4 ECD is a variant of an FGFR4 ECD fragment. In certain embodiments, the FGFR4 ECD is an FGFR4 2Ig ECD. In certain embodiments, the FGFR4 ECD is a native FGFR4 2Ig ECD. In certain embodiments, the FGFR4 ECD is an FGFR4 2Ig ECD variant. In certain embodiments, the FGFR4 ECD is an FGFR4 ECD acidic region mutein. In certain embodiments, the FGFR4 ECD is an FGFR4 ECD D1-D2 linker chimera. In certain embodiments, the FGFR4 ECD is an FGFR4 ECD glycosylation mutant. In certain embodiments, the amino acid sequence of the FGFR4 ECD is at least 80% identical to SEQ ID NO: 1, 2, 3, or 4. In certain embodiments, the amino acid sequence of the FGFR4 ECD is at least 85% identical to SEQ ID NO: 1, 2, 3, or 4. In certain embodiments, the amino acid sequence of the FGFR4 ECD is at least 90% identical to SEQ ID NO: 1, 2, 3, or 4. In certain embodiments, the amino acid sequence of the FGFR4 ECD is at least 95% identical to SEQ ID NO: 1, 2, 3, or 4. In certain embodiments, the amino acid sequence of the FGFR4 ECD is at least 99% identical to SEQ ID NO: 1, 2, 3, or 4. In certain embodiments, the amino acid sequence of the FGFR4 ECD has an amino acid sequence of SEQ ID NO: 10. In certain embodiments, the amino acid sequence of the FGFR4 ECD has an amino acid sequence of SEQ ID NO: 29. In certain embodiments, the FGFR4 ECD lacks a signal sequence. In certain embodiments, the FGFR4 ECD comprises a signal sequence. In certain embodiments, the signal sequence is the native signal sequence of FGFR1, FGFR2, FGFR3, or FGFR4. In certain embodiments, the signal sequence is not an FGFR signal sequence. In certain embodiments, the subject is a rodent, simian, human, feline, canine, equine, bovine, porcine, ovine, caprine, mammalian laboratory animal, mammalian farm animal, mammalian sport animal, or mammalian pet. In certain embodiments, the subject is a human. In certain embodiments, the administering is intravenous, subcutaneous, intraperitoneal, topical, or transdermal.
In certain embodiments, a method of growing hair comprising administering an FGFR4 ECD fusion molecule to a subject in an amount sufficient to promote hair growth is provided. In certain embodiments, the FGFR4 ECD fusion molecule comprises an FGFR4 ECD polypeptide and a fusion partner. In certain embodiments, the FGFR4 ECD polypeptide is a native FGFR4 ECD. In certain embodiments, the FGFR4 ECD polypeptide is an FGFR4 ECD variant. In certain embodiments, the FGFR4 ECD polypeptide is an FGFR4 ECD fragment. In certain embodiments, the FGFR4 ECD polypeptide is a variant of an FGFR4 ECD fragment. In certain embodiments, the FGFR4 ECD polypeptide is an FGFR4 2Ig ECD. In certain embodiments, the FGFR4 ECD polypeptide is an FGFR4 ECD acidic region mutein. In certain embodiments, the FGFR4 ECD is an FGFR4 ECD D1-D2 linker chimera. In certain embodiments, the FGFR4 ECD is an FGFR4 ECD glycosylation mutant. In certain embodiments, the fusion partner is selected from an Fc, albumin, and polyethylene glycol. In certain embodiments, the fusion partner is an Fc. In certain embodiments, the FGFR4 ECD fusion molecule has an amino acid sequence of SEQ ID NO: 15. In certain embodiments, the FGFR4 ECD fusion molecule has an amino acid sequence of SEQ ID NO: 52. In certain embodiments, the FGFR4 ECD fusion molecule lacks a singal sequence. In certain embodiments, the FGFR4 ECD fusion molecule comprises a signal sequence. In certain embodiments, the signal sequence is the native signal sequence of FGFR1, FGFR2, FGFR3, or FGFR4. In certain embodiments, the signal sequence is not an FGFR signal sequence. In certain embodiments, the subject is a rodent, simian, human, feline, canine, equine, bovine, porcine, ovine, caprine, mammalian laboratory animal, mammalian farm animal, mammalian sport animal, or mammalian pet. In certain embodiments, the subject is a human. In certain embodiments, the administering is intravenous, subcutaneous, intraperitoneal, topical, transdermal, or intradermal.